Method of forming or working metal elements



March 17, 1942. H. w. STARK 2,276,521

METHOD OF FORMING OR WORKING METAL ELEMENTS Filed April 22, 1940 G /2 (gm A? l6 @J yvvw INVENTOR.

Patented Mar.- 17, 1942 UNITED STATES, PATENT OFFI E- METHOD OF FORMING on WORKING METAL ELEMENTS Harold w. Stark, Detroit, Mich. Application April 22, 31940, Serial No. 330,841

5 Claims.

[This invention relates to a process for the forming or working of metal elements, as for instance, in the making of cap scrQws, bolts, studs and the like from rodor wire stock. It has been commonly the practice to head or otherwise shape screw blanks, bolts, studs and the like by forging the same while cold; which forging has usually'been performed by a series of steps and oftentimes the formed portion tends the article which results in considerable labor cost. a

By my improved process wherein articles are formed from rod or wire stock of the desired shape in cross section, the rod is fed into a high frequency induction coil wherein it remains for gized and de-energized at the proper time.

to provide a means, such as the opposed rollers Q I and 2 of Fig. 1, for intermittently feeding a rod 3 forwardly, in the direction of the arrow shown, with the projecting end of the rod engaging a stop 4. If it is desired to heat the 'end of the rod, the coil 5 of a high frequency circuit, diagrammatically indicated at 6, is. positioned to receive the end of the rod projected thereinto by the rolls into engagement with the stop 4.

The circuit is preferably intermittently enerhave here shown a manually operable switch for opening and closing the circuit through the coil inasmuch as the process is not confined to the specific character of the mechanical elements. I have also indicated a reciprocable cutter 8 adjacent the rolls which cooperates with a holder 9 in the usual manner and is movable in the direction of the arrow on the cutter. 8 to sever a slug from the stock. {Assuming'that a slug has been cut from the stock, the end of the rod would be at the right hand end of the shear block 9. 'The rolls are then operated to move the rod 3 in the direction of the arrow and, prior to'the end of the rod entering the end of the coil 5, the

circuit is closed thereby heatingthe end of the the period of time required to heat the part to. the desired depth for the character of Work to be performed thereon the rod then being severed to provide desired lengths of slug and passing the heated slug to the machine for working the heated portion of the same.

These and other features. and objects of the invention are hereinafter more fully described 1 and claimed and the preferred means for and method of heating metal articles preparatory to the forming and shaping step is shown in the accompanying drawing in which Fig. 1 is a diagrammatic view illustrating the arrangement of parts for heating a portion of the workpiece to be severed from a rod for a subsequent forming operation.

Fig. 2 is a diagram showing the arrangement of parts for heating a portion of a rod at several spaced points whereby, in movement of the rod. a portion thereof requiring tobe shaped may be heated in stages whereby the said portion thereof maybe heated to a higher'degree of temperature than is secured by the arrangement shown in Fig. 1.

Fig. 3 is a diagrammatic end-view of the heatin! coil. I

No attempt is here made toshow the machine proper. It is, however, usual in such machines rod as it moves into the coil to engagement with the stop at which time the slug 3a is severed. from the rod and moved therefrom to the machine for heading or otherwise working the 1 heated portion. The heating thereof is localized and, due to the use of a high frequency induction "coil, the heating is very rapid thereby softening the metal-to a depth determined by the period of heating. The slug-may then be worked more readily than is the case with, the cold heading process without danger of fracture and without necessity of submitting the slug to several forming steps to secure the final shape. -It is further pointed out that the heated portion of the slug may be submitted .to a threading operation .by rolling the same between threading dies subsequent to heating and severance from the rod 3.

The previous method of threading the slug by rolling the samebetween threading dies has, heretofore been performed when the part is cold.

By performing the step of threading while the portion'to be threaded is comparatively soft, the

threading can be performed more rapidly and with less liability of weakening the parts by displacement oflthe molecules than is the case with .the cold rolling process. For the performance of the method as above described, the coil hasanopen side l0 slightly-greater in width than the diameter of the slug 3a positioned centrally therewithin as shown in Fig. 3; This arrangement permits the severed slug tobe moved laterally from the coil for the working step, that is, either threading or heading or otherwise shaping the heated portion.

Some operations require heating to a greate degree than is provided for in the arrangement shown in Fig. 1 except that it is possible to maintain the circuit and coil 5 energized-for a sufficient period to secure the desired depth to which the slug is'heated. Such arrangement would require a greater time period during which the' slug is in the coil and therefore reduce the number of pieces produced per time period.

To increase the number of pieces per time period the heating may be accomplished by the arrangement shown in Fig. 2 wherein is shown a series of coils ll, l2 and I3, each of the same character as that heretofore described and arranged in longitudinally spaced relation on the rod I4 which may be fed in the direction of the arrow by rolls I5, l6, and rolls I! and i8 to engagement with the stop IS.

The slug shown at may be severed by the cutter 2| as above described relative to the cutter 8 of Fig. 1. The coil I3 is at the end of, the rod to be heated and the coils l2 and II are positioned on the rod in such relation that these coils are heating a portion of the rod that will finally be introduced into the coil l3. moved step by step by the rollers, there being suflicient pause between the steps to permit the severing of the end slug, as for instance 20, from the rod at the final heating step. Thus the heating may be performed in a single or a series of steps depending largely upon the diameter of the stock and the extent to which it is desirous to soften the material prior to passing the same to a device for forging or otherwise working the slug.

There are many articles to be formed from rod stock wherein the portion to be formed is between the ends thereof, as for instance, to make The rod is My improved method does not result in surface scaling of the heated parts due to the practically instantaneous heating of smaller articles such as screw and bolt blanks and the like and inasmuch as the heated part projects from the holding die, used in the forming step, it is the unheated par that fit in the die.

It is further pointed out that blanks and various articles to be formed do not require normalizing as is now commonly the case as by the method herein described the heating of the part v to be formed is, for articles of the size of such blanks, about one second and thus there is no opportunity for scale to form as the part is immediately submitted to the forming operation.

Upon completion of the forming step the part other desirable result as the article to be formed is only heated for a distance from the surface inwardly. This is of particular value in the formation of threaded cap screws, bolts and the like as the core has not been changed in its original'molecular structure. It is only the surface that has been heated and hardened by my process and therefore there is less liability of breakage because of the softer core.

While I have shown an open sided coil of a high frequency alternatingcurrent circuit such form of coil is desirable where it is necessary to remove the article laterally from the coil for a subsequent forming operation, as is the case with screw blanks, bolts and the like, hereinbefore mentioned. Insofar as the process is concerned,

- however, other forms of coil may be used, such an enlargement on the central portion of the rod I stock are partially, if 'not wholly, automatic in operation and such machines could be adapted to utilize my improved process by provision of the proper coils and thus adapting the same for heating the work piecesor slugs preparatory to a subsequent forming operation.

The process, however, is not confined to the formation of articles from rod stock. Many sheet metalparts, for instance, in shaping to the required form in a press are of such character that .unusual strain is imposed upon the piece at certain points. The invention herein disclosed may be used for such an article as the metal sheet to be passed to the press for shaping may have such portions thereof subject to an undue strain first passed through a coil or coils to thereby heat such areas just as the parts are passed to the press. The softening of such treated portions of the metal sheet permits the metal to as a coil having separable parts to permit introduction of a metal piece therewithin.

Other means, within the spirit and scope of field which is being reversed several thousand times a second thereby causing friction between the molecules and generating heat. Therefore it is to be realized that many changes, within the spirit and scope of the invention as defined by the appended claims, may be made in the arrangement and structure of the parts of the the forming or shaping operation, what I claim and desire to secure by Letters Patent of the United States ismore readily flow in the formation thereof and .thus prevent fracture which might otherwise occur in the forming operation.

The process as hereinbefore described is superior to the previous processes in which the parts are heated in a furnace and then forged, which former method is productive of a scale 1. In apparatus for heat treating blanks to be cut from rod stock for the subsequent formation of-articles, a series of high frequency coils of equal length arranged in axial alignment and in equi-spaced relation through which the stock is moved, a stop against which the end ofthe stock engages, a heating coil at the stop into which the end of the stock is introduced, a cutting means for severing the stock at the un- "heated portion thereof adjacent the coil at the stop, and means, for moving the stock step by step between the cutting operations to bring successive portions thereof to the cutting means, the series of high frequencyqoils being spaced apart a distance greater than the portion thereof to be heated by the coils and the parts being so arranged that the portion of the rod heated by the first coil of the series is submitted to the heating operation by the remaining coils of the series including the heating coil at the stop and the cutting operation is performed on the unheated portion of the stock.

2., In an apparatus for heat treating blanks to be cut from rod stock for subsequent formation of articles, a series of high frequency induction coils arranged in axial alignment and in equispaced relation through which the stock is passed, means for feeding the stock step by step to position the portion of the stock heated by the first oi the series of coils to a heating operation at each of the remaining coils of'the series, means for cutting the stock, a stopagainst which the end of the stock is moved, a coil positioned about the stock from the end engaging the stop toward the cutter, the arrangement of the coils being such that the stock in the coilat the stop has been previously submitted to heating by the series of equi-spaoed coils, and the cutter being positioned to sever the stock at an unheated portion thereof between the coil at the stop and a succeeding portion of the stock heated by the preceding series of coils.

3. In apparatus for heat treating blanks cut from rod stock for subsequent formation of articles, a series of high frequency coils arranged in axial alignment and having similar ends thereof spaced at distance apart approximately equal to the length of the blank to be cut from the end thereof, a cutter across which the stock is movable, a stop beyond the cutter, a high frequency coil about the stock into which the rod is passed to engage the stop, the cutter being positioned to sever the stock at the unheated portion adjacent the coil at the stop.

4. In apparatus for heating rod stock to provide blanks for subsequent formation of articles, a'series of high frequency coils arranged in axial alignment and having similar ends thereof spaced a distance apart substantially equal to the length of the blank to be cut therefrom, a cutter to which the stock is fed, a stop at a distance from the cutter substantially equal to the said spacing. of the ends of said series of coils, and an open sided high frequency coil at the stop into which the portion of the stock previously heated by the said series of coils is positioned and wherein the portion of the stock within the coil is brought to desired final temperature previous to being severed from the stock, the position of the cutter being such that the stock is severed at a point'unheated by the coils, and the open sided coil permitting the heated blank to be ithdrawn laterally therefrom.

5. In apparatus for heating rod stock to provide blanks for the subsequent formation of articles, a cutter across which the stock is movable step by step, a stop against which the end of the stock is moved at each step, a high fre quency coil at the stop for heating the enri of the stock. for a distance from the stop toward the cutter and providing an unheated portion extending from the end of the coil to the cutter free from scale and unchanged in molecular structure.

HAROLD W. STARK. 

